Brake shoe and method for producing a brake shoe

ABSTRACT

In a brake shoe ( 1 ) comprising a carrier plate ( 2 ) having arranged thereon first a dampening and noise-reducing intermediate layer ( 4 ) and then a friction lining ( 6 ), it is provided that the intermediate layer ( 4 ), on the side thereof facing towards the friction lining ( 6 ), comprises a three-dimensional surface structure, and that the friction lining ( 6 ) on the carrier-plate side is adapted to the surface contour ( 5 ) of the intermediate layer ( 4 ).

BACKGROUND OF THE INVENTION

[0001] The invention relates to a brake shoe according to the preamble of claim 1, and a method for producing a brake shoe according to the preamble of claim 11.

[0002] It is already known to arrange a dampening intermediate layer between a carrier plate and a friction lining. This intermediate layer has a uniform layer thickness of 3 mm, for instance. This intermediate layer is useful, e.g., for bonding the friction lining to the carrier plate with high strength.

[0003] In known brake linings, undesired accompanying phenomena will occur during braking, depending on the wear condition of the brake shoe. With increased wear, for instance, brake shoes are known to contribute to a heightened generation of brake noises because the friction linings tend to become harder and lose compressibility with increased service life and thermal stress. For this reason, the friction linings will become less capable to adapt to the brake disks which undergo geometric changes (e.g. shield formation) under the influence of heat.

[0004] The generated noises can be characterized as follows:

[0005] crumpling (broad-band noise: 200 Hz to 8 kHz)

[0006] squeaking (1500 Hz to 15 kHz)

[0007] juddering (20 Hz to 100 Hz)

[0008] humming (200 Hz to 600 Hz), and

[0009] wire-brush noises.

[0010] Juddering effects such as vibrations of the steering wheel and pulsation of the brake pedal, as well as humming, can increase along with the progression of the wear condition.

SUMMARY OF THE INVENTION

[0011] It is an object of the invention to provide a brake shoe and a method, respectively, for producing a brake shoe, which make it possible to keep the development of noise and the transmission of vibrations onto the steering wheel or the brake pedal continuously low throughout the lifespan of the brake shoes.

[0012] The above object is solved by the features of claim 1 as well as of claims 11 to 16.

[0013] According to the invention, it is advantageously provided that the intermediate layer, on the side thereof facing towards the friction lining, comprises a three-dimensional surface structure, and that the friction lining on the side of the carrier plate is adapted to the surface contour of the intermediate layer. The intermediate layer is provided to exert a favorable influence on the stiffness of the brake lining in the radial direction and the tangential direction of the brake lining relative to the brake disk by influencing the compressibility and the dampening of the brake lining. In this manner, brake noises and the transmission of vibrations onto the steering wheel and the brake pedal can be reduced to a minimum.

[0014] A further objective resides in influencing the compressibility and thus the surface pressure in the axial direction. The influencing of the compressibility results in a high dampening of humming, squeaking and crumpling noises.

[0015] Preferably, the friction lining is soft and elastic in the tangential direction. Thereby, the tendency towards juddering can be reduced so that noises, rotational vibrations of the steering wheel and pulsation of the pedal will be decreased. In this arrangement, the friction lining can be relatively stiff in the radial direction.

[0016] The three-dimensional surface structure of the intermediate layer also influences the effective friction radius and the heat intake into the brake disk while the lining can optimally adapt to the geometric changes of the brake disk.

[0017] It is provided that the intermediate layer comprises a material which is soft relative to the friction lining and is highly dampening. By means of the three-dimensional surface structure, it is made possible to adjust the stiffness and dampening properties within wide ranges without changing the friction material. In this manner, also the friction behavior and the wear can be favorably influenced.

[0018] In a preferred embodiment, it is provided that the surface structure of the intermediate layer facing towards the friction lining comprises projections extending into the friction lining.

[0019] According to one embodiment, it can be provided that the projections extend into the surface of the friction lining.

[0020] The projections can have a bar-shaped, conical or sinusoidal cross-sectional shape.

[0021] Alternatively, the projections can have a cylindrical shape. The three-dimensional surface structure of the intermediate layer can be oriented symmetrically relative to a radial axis of symmetry of the carrier plate. This radial axis of symmetry is related to the rotational axis of the wheel and the brake disk, respectively.

[0022] In an alternative embodiment, it is provided that the projections are arranged asymmetrically relative to the radial axis of symmetry of the carrier plate. By use of the symmetrical or asymmetrical arrangement of the projections of the intermediate layer, the direction-dependent stiffness of the friction lining can be adapted to different requirements.

[0023] In one embodiment, it is provided that the side of the intermediate layer facing towards the friction lining is inclined relative to the carrier plate and forms a wedge-shaped intermediate layer having a three-dimensional surface structure.

[0024] The wedge-shaped orientation of the surface structure can be provided relative to a radial axis of symmetry of the carrier disk and/or to an axis which is orthogonal to the axis of symmetry and parallel to the carrier plate.

[0025] In a preferred method for manufacturing a brake shoe, it is provided that, in a first press-molding step, the material of the intermediate layer is pressed to obtain a predetermined three-dimensional surface structure for forming an intermediate layer, while, in a second step, the friction material is introduced into the same mold and the friction lining together with the pre-molded intermediate layer and the carrier plate is finish molded.

[0026] In an alternative method for the production of a brake shoe, on the other hand, it is provided that, in a first step, the material of the intermediate layer is introduced into a mold and, by means of a vibrating or shaking die, is pre-molded to obtain a predetermined three-dimensional surface structure without being pressed, while, in a second step, the friction material for the friction lining is added and pre-molded, and that, in a third step, the pre-molded but not yet pressed material of the intermediate layer and the pre-molded friction material are together finish molded on the carrier plate a press mold by a sole press-forming step under the influence of heat and pressure.

[0027] In a further alternative method for the production of a brake shoe, on the other hand, it is provided that, in a first step, the material of the intermediate layer is pre-molded to obtain a predetermined three-dimensional surface structure for forming an intermediate layer, in a second step, the carrier plate and the prefabricated intermediate layer are inserted into a press mold, in a third step, friction material is filled into the press mold, and, in a fourth step, the friction lining is finish molded on the carrier plate under the influence of heat and pressure.

[0028] The following alternative methods are applicable particularly if the bottom of the press mold is formed by a press die and the upper end of the press mold is terminated by the carrier plate. In this case, the friction material is first introduced into the press mold.

[0029] Thus, in a further alternative method for the production of a brake shoe, it is provided that, in a first step, the friction material is filled into the press mold and is pre-molded to obtain a predetermined three-dimensional surface structure, in a second step, the material of the intermediate layer is filled onto the pre-molded friction material in the press mold and, in a third step, the friction lining is finish molded on the carrier plate by common press-molding of the pre-molded friction material and the material of the intermediate layer.

[0030] In a further alternative method for the production of a brake shoe, it is provided that, in a first press-molding step, the material of the intermediate layer is pre-molded to obtain a pre-molded three-dimensional surface structure for forming an intermediate layer, in a second step, the friction material is filled into the press mold, in a third step, the pre-molded intermediate layer is laid onto the friction material in the press mold and, in a fourth step, the friction lining is finish molded on the carrier plate by common press-molding of the pre-molded intermediate layer and the friction material.

[0031] In a further variant of a method for the production of a brake shoe, it is provided that, in a first press-molding step, the friction material is pre-molded to obtain a predetermined three-dimensional surface structure, in a second step, the pre-molded friction material is inserted into a press mold, in a third step, the material of the intermediate layer is introduced and, in a fourth step, the friction lining is finish molded on the carrier plate by common press-molding of the pre-molded friction material and the material of the intermediate layer.

[0032] Embodiments of the invention will be explained in greater detail hereunder with reference to the drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a view of a first embodiment of a surface structure of the intermediate layer of a brake shoe.

[0034]FIG. 2 is a view of a second embodiment.

[0035]FIG. 3 is a sectional view taken along the line III-III in FIG. 1.

[0036]FIG. 4 is a lateral view of a third embodiment.

[0037]FIG. 5 is a sectional view taken along the line V-V in FIG. 4.

[0038]FIG. 6 is a view of an embodiment with wedge-shaped surface structure of the intermediate layer.

[0039]FIG. 7 is a view of a further embodiment.

[0040]FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7.

[0041]FIG. 9 is a view of an embodiment with an asymmetrical arrangement of the surface structure.

[0042]FIG. 10 is a view of an embodiment with an symmetrical arrangement of the surface structure relative to a radial axis of symmetry of the brake shoe.

[0043]FIG. 11 illustrates different cross-sectional shapes of the projections of the intermediate layer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] The first embodiment of a brake shoe 1, shown in FIG. 1, comprises a metallic carrier plate 2 having first arranged thereon an intermediate layer 4 functioning as a dampening layer between the friction lining 6 and the carrier plate 2.

[0045] The intermediate layer 4 comprises, on the side thereof facing towards the friction lining 6, a three-dimensional surface structure 5 provided with projections 8 engaging the friction lining 6. The friction lining 6 is correspondingly adapted to the surface contour 5 of the intermediate layer 4 and comprises a friction material of the usual type.

[0046] In FIG. 1, the surface structure 5 of that side of the intermediate layer 4 which is facing towards the friction lining 6 is indicated by the interrupted line. Thus, the embodiment according to FIG. 1 presents a three-dimensional surface structure of the intermediate layer 4 which, when viewed in cross-section, has a wave shape. FIG. 3 is a sectional view taken along the line III-III in FIG. 1, from which it can be seen that the three-dimensional surface structure 5 comprises projections 8 extending into the friction lining 6. In FIG. 3, the projections 8 formed in the surface structure 5 are illustrated in a sectional view.

[0047] By means of the three-dimensional surface structure 5, the stiffness of the brake lining can be influenced in the radial direction as well as in the tangential direction. The accommodation of projections 8,8′,8″,8′″ in friction lining 6 makes it possible to keep the compressibility and dampening of brake shoe 1 constant throughout the service life of the brake shoes and thus to keep the noise development and the transmission of vibrations onto the steering wheel or the brake pedal low.

[0048] Further, the compressibility and dampening should be favorably influenced also in the axial direction. In this manner, brake noises such as humming, squeaking or crumpling can be minimized.

[0049]FIG. 2 shows a further embodiment of a brake shoe 1 with a surface structure 5 which, in cross-sectional view, comprises roof-shaped or prismatic projections 8′.

[0050]FIG. 4 shows a third embodiment comprising projections 8 having sinusoidal or triangular shapes as viewed in cross section, with the projections, in contrast to the embodiment according to FIG. 3, extending in a transverse direction relative to the radial axis of symmetry 10 of brake shoe 1. This can be best seen in FIG. 5 which is a sectional view taken along the line V-V in FIG. 4.

[0051] Illustrated in FIG. 6 is a fourth embodiment wherein the surface structure 5 extends at an inclination relative to the carrier plate 2, thus forming a wedge-shaped intermediate layer 4 with three-dimensional surface structure 5.

[0052] In this arrangement, the projections of the surface structure 5 can have any one of the various cross-sectional shapes illustrated in FIG. 11. The surface structure 5 can be inclined about one or two axes. For instance, the inclination can be adjusted relative to the radial axis of symmetry 10 and/or an axis which is orthogonal to this axis of symmetry 10 and parallel to the carrier plate 2.

[0053] The embodiment according to FIGS. 7 and 8 presents a surface structure 5 comprising dot-shaped projections 8″.

[0054]FIG. 7 is a sectional view taken along the line VII-VII in FIG. 8, and FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7.

[0055] The embodiment according to FIG. 9 presents an asymmetrical arrangement of the projections relative to the radial axis of symmetry 10. The pattern of the arrangement of projections 8,8′,8″,8′″ depends on the individual properties of the brake and the brake disk with regard to the construction and the vibration characteristics in combination with the friction material of the friction lining.

[0056]FIG. 11 shows different cross-sectional shapes of the projections 8,8′,8″,8′″. The projections 8 are elongate, bar-shaped projections as illustrated e.g. in FIGS. 3 or 5 while the projections 8′, 8″ and 8′″ are dot-shaped projections.

[0057] On the other hand, the cross-sectional shapes of the projections 8′,8″,8′″ can also be cross sections of bar-shaped projections, as shown in FIG. 2. A sectional view of the embodiment according to FIG. 2 with triangular cross-sectional structure of the projections 8′ would result in a similar cross-sectional configuration as in FIG. 3.

[0058] A preferred composition of intermediate layer 4 comprises:

[0059] 0-40% by weight: metals

[0060] 10-60% by weight: fillers

[0061] 5-25% by weight: organic additives

[0062] 0-10% by weight: organic/anorganic fibers.

[0063] It is essential that the intermediate layer as a binder layer does not contain any lubricants. 

What is claimed is:
 1. A brake shoe (1) comprising a carrier plate (2) having arranged thereon first a dampening and noise-reducing intermediate layer (4) and then a friction lining (6), characterized in that the intermediate layer (4), on the side thereof facing towards the friction lining (6), comprises a three-dimensional surface structure, and that the friction lining (6) on the carrier-plate side is adapted to the surface contour (5) of the intermediate layer (4).
 2. The brake shoe according to claim 1, characterized in that the intermediate layer (4) comprises a material which is soft relative to the friction lining (6) and is highly dampening.
 3. The brake shoe according to claim 1 or 2, characterized in that the surface structure (5) of the intermediate layer (4) facing towards the friction lining (6) comprises projections (8,8′,8″,8′″) engaging the friction lining (6).
 4. The brake shoe according to claim 3, characterized in that the projections (8,8′,8″,8′″) extend into the outer surface of the friction lining (6).
 5. The brake shoe according to claim 3 or 4, characterized in that the projections (8,8′,8″,8′″) have a bar-shaped, conical or sinusoidal cross-sectional shape.
 6. The brake shoe according to claim 3 or 4, characterized in that the projections (8′″) have a cylindrical shape.
 7. The brake shoe according to any one of claims 1 to 6, characterized in that the three-dimensional surface structure (5) of the intermediate layer (4) is oriented symmetrically to a radial axis of symmetry (10) of the carrier plate (2).
 8. The brake shoe according to any one of claims 3 to 7, characterized in that the projections (8) are arranged asymmetrically relative to the radial axis of symmetry (10) of the carrier plate (2).
 9. The brake shoe according to any one of claims 1 to 8, characterized in that the surface structure (5) of the intermediate layer (4) facing towards the friction lining (6) is inclined relative to the carrier plate (2) and forms a wedge-shaped intermediate layer (4).
 10. The brake shoe according to claim 9, characterized in that the surface structure (5) of the intermediate layer (4) facing towards the friction lining (6) is inclined relative to a radial axis of symmetry (10) of the carrier disk (2) and/or to an axis which is orthogonal to the axis of symmetry (10) and parallel to the carrier plate (2).
 11. A method for producing a brake shoe (1) wherein a friction material and an intermediate-layer material between the friction material and a carrier plate (2) is filled into a press mold and is pressed into a friction lining (6) on the carrier plate (2) under the influence of pressure and heat, characterized in that, in a first press-molding step, the intermediate-layer material is pressed in the press mold to obtain a predetermined three-dimensional surface structure (5) for forming an intermediate layer (4), and that, in a second step, the friction material is introduced into the same press mold and the friction lining (6) together with the pre-molded intermediate layer (4) and the carrier plate (2) is finish molded.
 12. A method for producing a brake shoe (1) wherein a friction material and an intermediate-layer material between the friction material and a carrier plate (2) is filled into a press mold and is pressed into a friction lining (6) on the carrier plate (2) under the influence of pressure and heat, characterized in that in a first step, the intermediate-layer material is introduced into the mold and, by means of a vibrating or shaking die, is pre-molded to obtain a predetermined three-dimensional surface structure, in a second step, the friction material for the friction lining is added and pre-molded, and in a third step, the pre-molded but not yet pressed intermediate-layer material and the pre-molded friction material are together finish molded on the carrier plate (2) in the press mold by a sole press-forming step under the influence of heat and pressure.
 13. A method for producing a brake shoe (1) wherein a friction material and an intermediate-layer material between the friction material and a carrier plate (2) is filled into a press mold and is pressed into a friction lining (6) on the carrier plate (2) under the influence of pressure and heat, characterized in that in a first step, the intermediate-layer material is pre-molded to obtain a predetermined three-dimensional surface structure (5) for forming an intermediate layer (4), in a second step, the carrier plate (2) and the prefabricated intermediate layer (4) are inserted into the press mold, in a third step, friction material is filled into the press mold, and, in a fourth step, the friction lining (6) is finish molded on the carrier plate (2) under the influence of heat and pressure.
 14. A method for producing a brake shoe (1) wherein a friction material and an intermediate-layer material between the friction material and a carrier plate (2) is filled into a press mold and is pressed into a friction lining (6) on the carrier plate (2) under the influence of pressure and heat, characterized in that in a first step, the friction material is filled into the press mold and is pre-molded to obtain a predetermined three-dimensional surface structure, in a second step, the intermediate-layer material is filled onto the pre-molded friction material in the press mold, and in a third step, the friction lining is finish molded on the carrier plate by common press-molding of the pre-molded friction material and the intermediate-layer material.
 15. A method for producing a brake shoe (1) wherein a friction material and an intermediate-layer material between the friction material and a carrier plate (2) is filled into a press mold and is pressed into a friction lining (6) on the carrier plate (2) under the influence of pressure and heat, characterized in that in a first press-molding step, the intermediate-layer material is pre-molded to obtain a pre-molded three-dimensional surface structure for forming an intermediate layer, in a second step, the friction material is filled into the press mold, in a third step, the pre-molded intermediate layer is laid onto the friction material in the press mold, and in a fourth step, the friction lining is finish molded on the carrier plate by common press-molding of the pre-molded intermediate layer and the friction material.
 16. A method for producing a brake shoe (1) wherein a friction material and an intermediate-layer material between the friction material and a carrier plate (2) is filled into a press mold and is pressed into a friction lining (6) on the carrier plate (2) under the influence of pressure and heat, characterized in that in a first step, the friction material is pre-molded to obtain a predetermined three-dimensional surface structure, in a second step, the pre-molded friction material is inserted into a press mold, in a third step, the intermediate-layer material is introduced, and in a fourth step, the friction lining is finish molded on the carrier plate by common press-molding of the pre-molded friction material and the intermediate-layer material. 